Ancestry.co.uk have today extended their London Parish Records Collection with the addition of approximately 224,000 names of non-conformists worshippers from the collections of the London Metropolitan Archives.
The London Non-Conformist Registers collection includes baptism, marriage and burial registers from a large number of churches of various denominations, and dating from 1694 to 1921. Obviously not every church will have records covering the entire date range, so always check that the period you are interested in is covered.
So if your ancestors were Presbyterians, Congregationalists, Baptists, Quakers, Methodists and Unitarians and they lived in the capital, then there is a good chance you will find their records here. In some cases this might be the only record, or in some cases you might be able to avoid the cost of a marriage certificate by finding the marriage entry in the register.
Personally although I have a few non-conformists in my tree, it doesn’t look like any of them made their way to London and it doesn’t look like any of my London ancestors were non-conformists either. Never mind, you can’t win them all. I hope you have better luck than me.